Harmonic producer



July 1, 1930. QHL 1,769,270

I 'IARMON I C PRODUCER Filed "Sept. 23, 1926 INVENTQR.

A TToR latentecl July 1 UNITED STATES IwssELL s. OHL, 01? NEW YoRK, N. Y., ASSIGNOR 'ro AMERICAN TELEPHONE AND TELE- PATENT j omcs I GRAPH,COMP.ANY, A' CORPORATION OF NEW YORK I-IARMQNIG PRODUCER Application filed September 23, 1926. Serial No. 137,375. i

This invention relates to alternating current generators, and more particularly to arrangements for efiiciently generating hlgh frequency energy at high energy levels.

I. 5 High frequencyenergy may be generated by. any well known oscillator which may be, for example, of vacuum tube type. High frequency energy so generated often is of rather low energy level andfof somewhat variable frequency. Yet such high frequency energy maybe maintained constant in frequency only with considerable difficulty with the aid of additional apparatus. Moreover, the energy level may be raised by adding several stages of amplifiaction to the oscillator. Nevertheless, a system including such an oscillator and several stages of amplification is known to be very ineflicient Accordingly, it is one of the objects of thisinvention to produce high frequency energy at high energy levels with higher efficiency than has heretofore been possible. It is another object of this invention to 5 so relate a source of high frequency energy of definite frequency and. of low level to a source of high frequency energy of sub-. stantially equal frequency and. of high level that the energy of definite frequency will I synchronize the energy of substantially equal frequency and, moreover, become 1n- -tegrated with it.

- And it is 'a further object of this invention to relate a low frequency oscillator to a vacuum tube system acting as a distortion device to produce a harmonic of-the low frequency energy, so that the energy of the harmonic'of the low frequency may be employed to synchronize, and to become in: tegrated with, a wave of high frequency and of high energy level.

' While this invention will bepointed out with particularity in the appended claims,

the invention itself, both as to its further objects and features, will be better understood from the detailed description hereinafter following, when read in connection with the accompanying drawing, showing one embodiment of the invention merely for the purpose of illustration.

denser C and the resistance R having such Referring to the drawing, analternating current oscillator or generatoris designated by the reference character 0, which oscil-' lator or generator supplies current of fundamental frequency to the system. It will be understood that while this generator has been shown as a simple alternating current generator merely for the purpose of illustrati0n,any other oscillator well known in the art may equallywell be employed instead thereof, withinthe scope of this invention.

The oscillator O is connected to an inductance L which inductance is coupled to another inductance L The inductance L is employed to transmit the fundamental frequency of the oscillator O to a vacuum tube circuit which includes a vacuum tube V working on the thermionic principle, including an anode, a cathode and a'grid or control electrode. More specifically, the inductance L transmits the fundamental frequency of the oscillator O to the. grid and jtance L and serves the two-fold purpose of tuning the circuit to the frequency" of the oscillator. 0,. and of providing av suitable impedance relationship between the oscillator O andthe grid and cathode of the vacuum tube V A condenser 0 represents the inherent capacity between the anode and grid electrode of the vacuum tube V including the capacity of. the leads connected thereto.

- Another vacuum tube circuit is employed herein to produce high frequency energy at a comparatively high energylevel, the frequency of which may be somewhat different 339 trode.

from the frequency of one of the harmonicsof the fundamental frequency produced by the vacuum tube circuit described hereinabove. This circuit comprises another vacuum tube V also working on the thermionic principle, including also an anode, a cathode, and a grid or control elec- The cathodes of the vacuum tubes V and V are both heated to an electron- "emitting temperature by current from a battery B Two mutually reactive inductan'ces L and L may be considered connected, respectively, between the grid and cathode and the anode and cathode of the vacuum tube V These inductances are shunted by a variable condenser C so that a tuned circuit is provided, having substantially no reactanceat a frequency which may be substantially equal to, though somewhat different from, the frequency of a desired harmonic of the oscillator'O. A battery B supplies space potential to the anodes of the vacuum tubes V and V through inductance L .A resistance R, is connected between the grid electrode of the vacuum tube V and ground so as to provide the proper bias for the grid electrode, to thereby substantially prevent the production of harmonics of the frequency sustained by the latter vacuum tube circuit. A. condenser C is connected between the grid of the vacuum tube V and the grid of the vacuum tube V and acts to neutralize the inherent capacity between the anode and grid electrode of the vacuum tube V represented by the condenser C Consequently the current flowmg through the condenser C is substantially equal in magnitude and opposite 1n phase to the current flowing within the vacuum tube V by virtue of the inherent capacity between the anode and the grid electrode of said vacuum tube. Another condenser C is connected between the leftfundamental frequency of the oscillator O.

This harmonic, or harmonics, flows between the anode and cathode of the vacuum tube V The vacuum tube circuit, including the vacuum tube V acts as an oscillator to sustain oscillations of a high frequency and of high energy level, the frequency of which may be substantially equal to, though somewhat dilferent from, the frequency of the harmonic produced by the vacuum tube V acting as a distortion device. Moreover, the vacuum tube oscillator V is'rendered substantially free from tl e production of harmonics of its characteristic frequency by the provision of the resistance R, which maintains the grid electrode of the vacuum tube V suitably biased with reference to its cathode. However, the output circuits, which include the anodes of the vacuum tubes V and V,, are tiedtogether so that these vacuum tubes are effectively in parallel relationship with each other. Consequently, current generated byrthe vacuum tube oscillator V will be synchronized by the harmonic of the fundamental frequency produced by the vacuum tube V assuming of course thatthe output circuit of the vacuum tube V is tuned to a frequency, which is approximately equal to the frequency of, the current generated by the vacuum tube .oscillator V If, for. example, the frequency of the generator 0 is substantially equal to half of the frequency ofthe current generated by the vacuum tube oscillator V then at every second cycle current in the output circuit 'of-the vacuum tube V will be transmitted to the output circuit of the vacuum tube V Thus, it can readily be understood that the current of a-harmonic -of a fundamental frequency will be utilized to synchronize, and to become integrated with, current of an oscillator having a frequency substantially equal to that of the harmonic. q 4

lVhile. this invention has been shown in one particular embodiment merely for the purpose of illustration, it is to, be understood that the general principles of this invention may be applied to other and widely varied organizations without. departing .from the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. The combination of two vacuum tubes theoutput circuits of which are in parallel relationship with each other, one tube having a fundamental frequency impressed thereon, means whereby the other tube may enerate a fre uenc which is'a harmonic 115 of the fundamental frequency, and means associated with the first tube for producing the same harmonic of the, fundamentalfrequency, the eii'ectsofsaid tubes being-efiectively synchronized.

2. The combination of a vacuumtube circuit including a cathode, an anode and a control electrode, an oscillator of fundamental frequency, a resistance connected between vacuum tube circuitof such magniture that the control electrode becomes highly negative with respect to the cathode when energy of the fundamental frequency is imthe control electrode and the cathode of said 3125 pressed thereon, means for impressing the A30 fundamental frequency on said vacuum tube circuit, said vacuum tube circuit acting to produce a harmonic of the fundamental frequency, a second vacuum tube circuit also including a cathode, an anode and a control electrode, two mutually reactive inductances one interconnecting the control electrode and the cathode and the other interconnecting the anode and the cathode of the second vacuum tube circuit, a capacitative reactance of suitable magnitude so related to said inductances as to bring them into resonance at a frequency substantially equal to the harmonic of the fundamental frequency, and means interconnecting the anodes of said vacuum tube circuits so that the currents flowing between said anodes and the corre sponding cathodes are brought into synchronism.

3. The combination of a generator of a fundamental frequency, a vacuum tube generator of a harmonic of the fundamental frequency, and means including a vacuum tube for converting the fundamental frequency into a harmonic of the fundamental frequency equal to the harmonic generated by the vacuum tube generator, the output circuits of the vacuum tube of said converting means and of the vacuum tube generator being interconnected in parallel relation whereby stabilization of the harmonic of the fundamental frequency will take place.

4:. The combination of a first vacuum tube oscillator capable of generating current of a high frequency, a second oscillator capable of generating current of a frequency which is fundamental to the frequency of the first oscillator a vacuum tube circuit acting as a distortion device to produce a harmonic of the fundamental frequency substantially equal in frequency to the high frequency generated by the first oscillator,and means interconnecting the plate andfilament elec trodes of the vacuum tube of the first oscillator in parallel relation with the plate and filament electrodes of the vacuum tube circuit acting as a distortion device so that the frequency of the first oscillator will be in synchronism with the harmonic produced by said vacuum tube circuit.

5. The combination of a three-element vacuum tube system generating a wave of definite frequency of low energy level, another three-element vacuum tube system generating oscillations of hi h energy level of any frequency within de nite frequency limits, the frequency of said Wave of low energy level lying within said definite frequency limits, and means coupling the output circuits of said vacuum tube systems in parallel relation for bringing the oscillations of high energy level into synchronism with the oscillations of definite frequency of low energy level.

6. The combination of a source of current respective effects of said harmonic of definite 7 frequency and the wave of substantially equal frequency.

Intestimony whereof, I have signed my name to this specification this 21st day of September, 1926.

RUSSELL S. OHL.

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